From all I have read I don't believe GLBSE would just disappear overnight. Wat worries me is some individual(s) pulling a Maldoff.
GLBSE only hosts accounts for investor's balances (which the bitcoin funds can be used to buy shares or withdrawn). Once there is an IPO, the issuer gets those bitcoin funds.
In expressing your concern were you referring to GLBSE itself or an action by an asset issuer?